The present invention relates, in general, to control systems for powered doors and, more particularly, the instant invention relates to a powered door control system for a passenger transit type vehicle.
Motor driven transit vehicle door systems require a system for detecting obstructions to protect a passenger who may be in the path of a door which is closing or opening as would be the case with outside sliding door(s). This requirement must be seriously considered because transit vehicle doors may be quite massive and such doors are generally moved quickly between the open and closed positions. Forces required for rapid movement of massive doors are generally sufficient to cause injury to a passenger. This would be the case, particularly, on the closing cycle when a passenger may be caught by the closing door(s).
Prior to the development of the present invention, one method which has been employed is to place leading edge sensors in the seals adjacent the edge of a door which closes against a stop or against another door. Such leading edge sensors are generally unreliable, in part because floating cables must be connected to the moving door panels. Any failure of the edge sensor, or the cable connecting it to the control system for the door, may result in a door which attempts to continue a closing stroke, even after contacting a passenger.
Sensing the torque of the motor by the current drawn by the motor is another previously employed method. This method has been found to be extremely inaccurate because the current drawn by the motor can vary widely due to aging and to temperature. As is generally well known, aging reduces the strength of the field magnet (generally a permanent magnet). Additionally, the normal friction which the motor must overcome due to the door suspension and the drive mechanism may also vary through a wide range. Furthermore, this method can only detect a very substantial impact.
In one aspect, the present invention is a method of detecting obstructions encountered by a motorized door. The method includes providing a signal processor with one or more signals indicative of a predetermined door speed and/or position profile for at least a segment of a stroke of the door. The profile providing an ideal speed and/or position versus an elapsed time since the beginning of the segment of the stroke. A door position signal communicated from a position encoder for the door is received into the signal processor. The method includes generating one or more signals indicative of either a velocity (or position change per unit time) of the door from the door position signal and generating a trajectory discrepancy signal indicative of an error between the velocity and/or position of the door and the ideal speed and/or position. A motor control signal is generated based on the trajectory discrepancy signal and the motor control signal is connected to the motor for the door. The method further includes performing one or more tests on either the trajectory discrepancy, the actual velocity and/or position of the door versus the ideal velocity and/or position to determine whether the door has encountered an obstruction. In that case an obstruction detection signal is generated. The obstruction detection signal is for communication to a brake to stop the door(s).
In another aspect, the invention is an apparatus for detecting obstructions encountered by motorized door(s). The invention includes means for providing a signal processor with one or more signals indicative of a predetermined door trajectory profile for at least a segment of a stroke of the door. Such predetermined door trajectory profile providing an ideal speed versus an elapsed time since a beginning of the segment of the stroke. The apparatus includes means for receiving into the signal processor a door position signal from a position encoder for the door(s) and provision for generating one or more drive signals indicative of the velocity of the door from the door position signals. The signal processor includes means for generating a trajectory discrepancy signal indicative of a either a velocity and/or position discrepancy between the desired trajectory of the door and the ideal trajectory. It has means for generating a motor control signal based on the trajectory discrepancy signal. The motor control signal is connected to a power amplifier that drives the motor for the door(s). The signal processor also has means for performing one or more tests on the trajectory profile to determine whether the door has encountered an obstruction and it includes means for generating an obstruction detection signal from the one or more test. The obstruction detection signal is for stopping the door.
It is, therefore, one of the primary objects of the present invention to provide an obstruction detection system and method for motorized door(s) which does not require the use of leading edge sensor(s).
Another object of the present invention is to provide an obstruction detection system for a motorized door which does not depend on a measurement of motor torque.
Still another object of the present invention is to provide an obstruction detection system for a motorized door which does not depend on motor current.
Yet another object of the present invention is to provide an obstruction detection system for a CPU controlled motorized door which does not place a significant workload on the CPU.
A further object of the present invention is to provide an obstruction detection system for a motorized door which has fail safe features.
It is an additional object of the present invention to provide an obstruction detection system for a motorized door which operates quickly upon encountering an obstruction.
Still yet another object of the present invention is to provide an obstruction detection system for a motorized door which can distinguish between friction and an obstruction.
A still further object of the present invention is to provide an obstruction detection system for motorized door(s) in which failure of the obstruction detection system prevents movement of the door(s).
Another object of the present invention is to provide a procedural obstruction detection system for motorized door(s) wherein obstruction detection and movement are controlled by the same components.
Yet another object of the present invention is to provide an obstruction detection system for a motorized door which may be used for either a door system employing a single door panel or a biparting door system having two door panels.
In addition to the various objects and advantages of the present invention which have been generally described above, there will be various other objects and advantages of the invention that will become more readily apparent to those persons who are skilled in the relevant art from the following more detailed description of the invention, particularly, when the detailed description is taken in conjunction with the attached drawing figures and with the appended claims.